Oil and natural gas production and/or storage facilities typically employ tanks for storing large volumes of oil and natural gas in liquid or gaseous form. Such tanks are also referred to as “production tanks” in the industry. Such tanks may also be used to store other chemicals.
Production tanks are often a source of hydrocarbon vapors or gases (collectively referred to herein as “fugitive gases” or “gases”) emitting into the atmosphere. Government agencies, such as the Colorado Department of Health, have begun to adopt regulations limiting emissions from production tanks Depending on temperature, color of production tank, orientation to the sun, and gravity of the containing liquids, coupled with the normal separator operations, the amount of gas may vary from minimal to in excess of 4 mcfd (million cubic feet per day). Typically, these gases have a very high BTU (British Thermal Unit) content. Capture and beneficial usage of these gases, as opposed to flaring, is both economical and environmentally advantageous.
Further, gas in production tanks that are open to the atmosphere (e.g., are allowed to breathe) may reach explosive limits within the production tank, such as when the gas pressure decreases below the UEL (upper explosive limits) of the gas. This condition can present a safety hazard.